Why does the demon prince of Tzeentch have such a shitty spell line?

Seriously, the lore of Tzeentch has some of the best direct damage spells in the game, meanwhile the demon prince of Tzeentch has gehenna's golden hounds? I was so disappointed when I ascended my chaos sorcerer lord of Tzeentch, only to find out I just lost all the good spells and now have to bring a sorcerer hero into the army. So disappointing!